Oligopeptides with fungicidal activity

Abstract: Oligopeptidic compounds having the general formula (I): K-[-A-] z -[-B-] w -L The compounds having general formula (I) are antifungals for agricultural purposes.

Description: The present invention relates to oligopeptidic compounds. More particularly, the present invention relates to oligopeptidic compounds having high antifungal activity, to a process for preparing them and to their use in agricultural field as fungicides. Therefore, the subject-matter of the present invention are oligopeptidic compounds having the general formula (I): K-[-A-] z -[-B-] w -L wherein: z and w are 1; A represents an aminoacidic portion having the general formula (II): wherein: R a represents a linear or branched C 3 -C 4 alkyl radical; R' represents a hydrogen atom; B represents an aminoacidic portion having the general formula (III): wherein: R b represents a phenyl radical, an aromatic heterocyclic radical or a naphthyl radical, with said phenyl, heterocyclic and naphthyl radicals being also optionally substituted; an aromatic benzofused five-membered heterocyclic radical containing from 1 to 2 heteroatoms, which may be the same or different from each other, selected from nitrogen, oxygen and sulfur, with said aromatic benzofused five-membered heterocyclic radical being also optionally substituted; m is 1 and n is 0; R" represents a hydrogen atom; L represents a moiety having the general formula (IV): wherein: E represents an either linear or branched C 1 -C 8 alkylene or haloalkylene chain; an omega oxa--C 2 -C 8 -alkyl chain; or a direct linkage; R 1 represents a hydrogen atom; a C 3 -C 6 cycloalkyl radical; a phenyl radical or an aromatic heterocyclic radical, with said phenyl and heterocyclic radicals being also optionally substituted; R 2 represents a hydrogen atom; a linear or branched C 2 -C 6 carboxyalkyl radical; a linear, branched or cyclic C 2 -C 6 carbamoyl radical; a cyano radical; or an halogen atom selected from fluorine, chlorine and bromine; X represents an -O- moiety; a -N(R 3 )- moiety or a -N(R 4 )-O- moiety; wherein: R 3 represents a hydrogen atom; a C 1 -C 3 alkyl or alkoxy radical; or, together with R 1 , represents a direct linkage or a C 2 -C 4 alkylene chain; R 4 represents a hydrogen atom; a C 1 -C 3 alkyl radical; or, together with R 1 , represents a direct Linkage; K represents a hydrogen atom; an either Linear or branched C 1 -C 4 alkyl radical; or a protective group having the general formula (V) : wherein: Y represents an oxygen atom; or a direct linkage; M represents an either linear, branched or cyclic C 1 -C 8 alkylene or haloalkylene chain; or a direct linkage; R 5 represents a hydrogen atom; an optionally substituted phenyl radical; an optionally substituted phenoxy radical; an optionally substituted thiazolic radical; a linear, branched or cyclic C 2 -C 6 carbamoyl radical; a linear, branched or cyclic C 1 -C 6 carbalkoxy radical; or a cyano radical; R 6 represents a hydrogen atom; a C 1 -C 3 alkoxy or haloalkoxy radical; an acetate radical; an acetamidic radical; or an halogen atom selected from fluorine,chlorine and bromine; suitable for use as antifungal agents in agriculture. The structure having the general formula (I) contains two or more chiral centres. Purpose of the present invention is to take into consideration both isomerically pure compounds having general formula (I), as well as mixtures thereof. The compounds having general formula (I) are. antifungal agents for agricultural purposes. By "aromatic heterocyctic radical", an aromatic 5-membered or 6-membered heterocyclic radical is understood, which contains from one to three heteroatoms, which may be the same or different from each other, and are selected from nitrogen, oxygen and sulfur. When a phenyl radical, an aromatic heterocyclic radical, a naphthyl radical or an aromatic benzofused five-membered heterocyclic radical containing from 1 to 2 heteroatoms, which may be the same or different from each other, is disclosed as being "optionally substituted", it should be understood that said radical may be substituted with one or more halogen atoms, which may be the same or different from each other, and are selected from fluorine, chlorine, bromine and iodine, or with one or more groups, which may be the same or different from each other, and are selected from either linear or branched C 1 -C 5 alkyl or haloalkyl radicals, either linear or branched C 1 -C 5 alkoxy or haloalkoxy radicals; C 3 -C 6 cycloalkyl or cycloalkoxy radicals; C 2 -C 5 carbalkoxy radicals; cyano radicals; methylene dioxyl radicals having the general formula (VI) : wherein: R 7 and R 8 , which may be the same or different from each other, represent a hydrogen atom, a fluorine atom; a C 1 -C 3 alkyl or haloalkyl radical. When a phenoxy radical or a thiazolic radical is disclosed as being optionally substituted, it should be understood that said radical may be substituted with one or more halogen atoms, which may be the same or different from each other, selected from fluorine, chlorine, bromine and iodine, or with a methyl or trifluoromethyl radical. Examples for R a radicals, when R a represents an alkyl radical, are: isopropyl, isobutyl, sec.-butyl, tert.-butyl, and so forth. Examples for aminoacidic radicals A, when R a represents an alkyl radical, are (in brackets, the short form is reported which is derived from the international symbology used for peptides): L-Valine (―L[Val]―), DL-Valine (―DL[Val]―), D-Valine (―D[Val]―), Leucine (―[Leu]―), Isoleucine (―[Ile]―), allo-Isoleucine (―a[Ile]―), tert.-Leucine (―[Tle]―), and so forth. Examples of aromatic five-membered or hexa-membered heterocyctic radicals containing from one to three heteroatoms, which may be the same or different from each other, and are selected from nitrogen, oxygen and sulfur, are: pyridine, pyrimidine, pyrrole, imidazole, triazole, thiazole, oxazole, isooxazole, and so forth. Examples of L, when X represents an oxygen atom, are: methoxy, ethoxy, isopropoxy, tert.-butoxy, benzyloxy, and so forth. Examples of L, when X represents a ―N(R 3 )― moiety, are: methylamino, isopropylamino, butylamino, octylamino, N,N-dimethylamino, piperidyl, morphol-4-yl, benzylamino, 4-chlorobenzylamino, 2,4-dichlorobenzylamino, α-methyl-4-chlorobenzylamino, α-methyl-4-bromobenzylamino, α-methyl-4-methoxy-benzylamino, α--methyl-4-trifluoromethylbenzylamino, thiazol-2-ylamino, imidaz-2-ylamino, α-cyanobenzylamino, α-cyanoisopropylamino, α-carbomethoxyethylamino, α-carboisopropoxy-ethylamino,α-carbomethoxyisobutylamino, 2-carboisopropoxypyrrolid-1-yl, α-(N-methylcarbamoyl)ethylamino, α-carbamoylethylamino, 2-(N,N-dimethylcarbamoylpyrrolid-1-yl), 2-(N,N-dimethylcarbamoylpiperid-1-yl), and so forth. Examples of L, when X represents an -N(R 4 )-O-moiety, are: methoxyamino, benzyloxyamino, N-methyl-N-benzyloxyamino, and so forth. Examples of K, when Y represents an oxygen atom, are: carbomethoxy, carboisopropoxy, carboisobutoxy, carbo-tert.-butoxy, carbobenzyloxy, carbophenoxy, and so forth. Examples of K, when Y represents a direct bond, are: acetyl, isobutanoyl, benzoyl, cyclopropanoyl, 2-methoxy-propanoyl, 2-acetamidopropanoyl, 2-carbomethoxyacetyl, and so forth. A Compound having the general formula (I) not illustrated in the examples, but equally interesting for its fungicidal activity, is (the compound reported hereinunder, is represented in accordance to the international symbology used for peptides): Me 2 ―CH―O―CO―[Val]―β[Phe]―NH―CH(Me)―pCl―phenyl; The compounds of general formula (I) according to the present invention can be obtained by means of several processes. When K is different from hydrogen, the compounds having general formula (I) can be obtained by means of a process which can be schematically shown as follows (i) : in which K, A, z, B and w have the same meaning as disclosed hereinabove (K different from hydrogen). The above schematized condensation reaction (i), is carried out by causing the aminoacidic derivatives (VII) to react with a condensation agent such as, e.g., dicyclohexylcarbodiimide or carbonyldiimidazole, in the presence of a polar solvent, e.g., tetrahydrofuran, and subsequently adding the aminoacidic derivatives (VIII). The reaction is carried out at a temperature comprised within the range of from -10°C to room temperature. After the addition of the aminoacidic derivative (VIII), the solution is kept with stirring during about 10-15 hours. The resulting compound having general formula (I) is usually purified by crystallization from a suitable solvent such as, e.g., ethylether, isopropylether, methanol, isopropanol, and so forth, or from a mixture of solvents such as, e.g., ethyl ether/methanol, ethyl acetate/hexane, and so forth. When z is 1, the aminoacidic derivative (VIIa) is obtained by means of a process which- can be schematized as follows (ii) : in which K and A have the same meaning as indicated hereinabove (K different from hydrogen). The condensation reaction (ii) schematized above, between chloride (IX) and the aminoacidic derivative (X) can be carried out both in the presence of protic solvents such as, e.g., water, and in the presence of such organic bases as, e.g., triethylamine or N,N―dimethylaniline as. well as in the presence of inorganic bases such as, e.g., sodium hydrogen carbonate, or sodium hydroxide, at a temperature comprised within the range of from -15°C, up to +25°C. When w is 1, the aminoacidic derivative (VIIIa) is obtained by means of a process which can be schematically shown as follows (iv): in which B and L have the same meaning as disclosed above. The reaction (iv) schematically shown above, between the aminoacidic derivative (XIII), protected at its aminic function by means of a benzylcarboxy (BOC) group and compound (XIV), is carried out by operating according to the same conditions as disclosed for the reaction shown Scheme (i). The protective group (BOC) on the resulting compound (XV) is subsequently removed by acidic hydrolysis in ethyl acetate, at room temperature, according to as reported in Bulletin of Chemical Society Japanese (1977), page 718. When K stands for hydrogen, the compounds having general formula (I) can be easily obtained by treating a compound having general formula (XVII): wherein tBut indicates tert-butoxy, A, z, B, w and L have the same meaning as disclosed above, with an acidic solution af aqueous ethyl acetate, at room temperature, according to as reported in Bulletin of Chemical Society Japanese (1977), page 718. [A] and [B] aminoacids, when they are not commercial products, can be prepared according to what disclosed in published papers, such as, e.g., in Houben-Weyl, "Methoden der Organischen Chemie", Vol. 15: Synthese von Peptiden I and II, (1974); Greenstein-Winitz, "Chemistry of The Aminoacids", (1961) John Wiley Inc.; Synthetic Communications (1993), pages 349-356; Tetrahedron Letters (1975), pages 4393-4394; Tetrahedron Letters (1988), pages 6465-6466. The compounds having general formula (I) display particularly high fungicidal activity against phytopathogenic fungi which attack vine, sugar beet, cereal, cucurbits and orchard crops. The plant diseases which can be combatted with the compounds having the general formula (I) according to the present invention are, e.g., the following: Plasmopara viticola on vines; Sphaerotheca fuliginea on cucurbits; Phythium on horticultural crops; Phytophthora Spp. on horticultural crops; Helminthosporium teres on cereals; Erisyphe graminis on cereals; Puccinia spp. on cereals; Septoria spp. on cereals; Rhynchosporium on cereals; Podosphera leucotricha on cereals; Uncinula necator on vines; Venturia spp. on fruit trees; Pyricularia oryzae on rice; Botrytis cinerea; Fusarium spp. on cereals, and so forth. The compounds having the general formula (I) are capable of displaying a fungicidal action with both curative and preventive character and, additionally, display a low toxicity for plants, or do not display any such toxicity at all. For practical uses in agriculture, having available fungicidal compositions containing one or more compounds having general formula (I), possibly also as an isomer mixture, as the active substance, is often useful. The application of these compositions can be carried out on any portions of the plant, e.g., on leaves, stems, branches and roots, or on the same seeds before sowing, or also to the locus on which the plant grows. Compositions can be used which appear as dry dusts, wettable dusts, emulsified concentrates, microemulsions, pastes, granulates, solutions, suspensions, and so forth: the selection of the type of composition will depend on the specific use. The compositions are prepared by any modalities known from the prior art, for example, by diluting or dissolving the active substance with a solvent means and/or a solid diluent, possibly in the presence of surfactants. As solid diluents, or carriers, the following can be used: silica, China clay, bentonite, talc, fossil meal, dolomite, calcium carbonate, magnesia, chalk, clays, synthetic silicate, attapulgite, sepiolite. As liquid diluents, of course beside water, several solvents can be used, e.g., aromatics (xylenes or mixtures of alkylbenzenes), chloroaromatics (chlorobenzene), paraffins (petroleum fractions), alcohols (methanol, propanol, butanol, octanol, glycerol), amines, amides (N,N―dimethylformamide, N―methylpyrrolidone), ketones (cyclohexanone, acetone, acetophenone, isoforone, ethylamylketone), esters (isobutyl acetate). As surfactants, there can be used sodium, calcium, triethanolamine or triethylamine salts of alkylsulfonates, alkylarylsulfonates, polyethoxylated alkylphenols, fatty alcohols condensed with ethylene oxide, polyoxyethylated fatty acids, polyoxyethylated sorbitol esters, lignine sulfonates. The compositions can also contain special additives for particular purposes such as, e.g., adhesion promoters, such as gum arabic, polyvinyl alcohol, polyvinylpyrrolidone. If so desired, to the compositions according to the present invention also other compatible substances can be added, such as, e.g., fungicides, phytoregulants, antibiotics, herbicides, insecticides, fertilizers. The concentration of active substance in the above said composition can vary within a wide range, according to the active compound, the crop, the pest, the environmental conditions and the adopted formulation type. In general, the active substance concentration is comprised within the range of from 0.1% to 95%, preferably of from 0.5% to 90%. The following examples are reported for illustrative purposes and shall not be construed as being Limitative of the present invention. EXAMPLE 1 Syntesis of N-(tert.-butyloxycarbonyl)-L-valinyl-DL-β-phenyl-β-alanine ester (Compound No. 1 ). An amount of 1.1 g of cyclohexylcarbodiimide was added to a solution, kept cooled at 0°C, obtained by mixing 0.9 g of tert.-butyloxycarbonyl-L-valine, 1.2 g of isopropyl 3-phenyl-3-aminopropanoate hydrochloride (β-pheny-β-alanine hydrochloride) and 0.46 g of triethylamine in 10 cm 3 in metilene chloride. After 1 hour at room temperature, the obtained solution is evaporated under reduced pressure and the resulting raw product is purified on silica, using a mixture of 3:7 ethyl acetate:hexane as the solvent. 1.5 g of desired compound is obtained in a yield of 85%. ([α]°(CH 2 Cl 2 ) = - 13.80°). EXAMPLES 2-41 By operating analogously to Example 1 the compound nos. 2-41 were prepared, the structures of which are reported in Tables 1-5 , together with their elemental analysis results. EXAMPLE 42 Determination of preventive fungicidal activity against downy mildew of vines (Plasmopara viticola). Leaves of vine plants cultivar Dolcetto, grown in pots inside a conditioned room (20±1°C, relative humidity 70%), are spray treated on both their leaf faces with compounds 1-41 in water-acetone solution at 20% acetone by volume. After a 24-hour stay in conditioned environment, on both leaf faces of the plants, an aqueous suspension of conidia of Plasmopara viticola (200,000 conidia per cm 3 ) is sprayed. The plants are kept in a moisture saturated environment, at 21°C, during the fungus incubation time. At the end of said time period (7 days), the fungicidal activity is evaluated according to a percent evaluation scale from 100 (healthy plant) to 0 (completely infected plant). All synthetized compounds displayed a higher control rate than 90, at their use concentration of 500 ppm. EXAMPLE 43. Determination of preventive fungicidal activity against cucumber powdery mildew (Sphaerotheca fuliginea). Leaves of cucumber cultivar Marketer, grown in pots inside a conditioned room (20±1°C, relative humidity 70%), are spray treated on both their leaf faces with compounds 1-41 in water-acetone solution at 20% acetone by volume. After a 24-hour stay in conditioned environment, on both leaf faces of the plants, an aqueous suspension of conidia of Sphaerotheca fuliginea (200,000 conidia per cm 3 ) is sprayed. The plants are kept in a moisture saturated environment, at 21 °C, during the fungus incubation time. At the end of said time period (8 days), the fungicidal activity is evaluated according to a percent evaluation scale from 100 (healthy plant) to 0 (completely infected plant). All synthetized compounds displayed a higher control rate than 90, at their use concentration of 1000 ppm.

Claims: Oligopeptidic compounds having the general formula (I): K-[-A-] z -[-B-] w -L wherein: z and w are 1; A represents an aminoacidic portion having the general formula (II): wherein: R a represents a linear or branched C 3 -C 4 alkyl radical; R' represents a hydrogen atom; B represents an aminoacidic portion having the general formula (III): wherein: R b represents a phenyl radical, an aromatic heterocyclic radical or a naphthyl radical, with said phenyl, heterocyclic and naphthyl radicals being also optionally substituted; an aromatic benzofused five-membered heterocyclic radical containing from 1 to 2 heteroatoms, which may be the same or different from each other, selected from nitrogen, oxygen and sulfur, with said aromatic benzofused five membered heterocyclic radical being also optionally substituted; m is 1 and n is 0; R" represents a hydrogen atom; L represents a moiety having the general formula (IV): wherein: E represents an either linear or branched C 1 -C 8 alkylene or haloalkylene chain; an omega-oxa-C 2 -C 8 alkyl chain; or a direct linkage; R 1 represents a hydrogen atom; a C 3 -C 6 cycloalkyl radical; a phenyl radical, or an aromatic heterocyclic radical, with said phenyl and heterocyclic radicals being also optionally substituted; R 2 represents a hydrogen atom; a Linear or branched C 2 -C 6 carboxyalkyl radical; a linear, branched or cyclic C 2 -C 6 carbamoyl radical; a cyano radical; or an halogen atom selected from fluorine, chlorine and bromine X represents an ―O― moiety; a ―N(R 3 )― moiety or a ―N(R 4 )―O― moiety; wherein: R 3 represents a hydrogen atom; a C 1 -C 3 alkyl or alkoxy radical; or, together with R 1 , represents a direct Linkage or a C 2 -C 4 alkylene chain; R 4 represents a hydrogen atom; a C 1 -C 3 alkyl radical; or, together with R 1 , represents a direct linkage; K represents a hydrogen atom; an either linear or branched C 1 -C 4 alkyl radical; or a protective group having the general formula (V): wherein: Y represents an oxygen atom; or a direct Linkage; M represents an either linear, branched or cyclic C 1 -C 8 alkylene or haloalkylene chain; or a direct linkage; R 5 represents a hydrogen atom; an optionally substituted phenyl radical; an optionally substituted phenoxy radical; an optionally substituted thiazolic radical; a linear, branched or cyclic C 2 -C 6 carbamoyl radical; a linear, branched or cyclic C 1 -C 6 carbalkoxy radical; or a cyano radical; R 6 represents a hydrogen atom; a C 1 -C 3 alkoxy or haloalkoxy radical; an acetate radical; an acetamidic radical; or an halogen atom selected from fluorine, chlorine and bromine; suitable for use as antifungal agents in agriculture. Compounds according to claim 1, in which the aromatic heterocyclic radical, is a 5- or 6-membered aromatic heterocyclic radical containing from 1 to 3 heteroatoms, which may be the same or different from each other, selected from nitrogen, oxygen and sulfur. Compounds according to claim 1, in which the phenyl radical, the aromatic heterocyclic radical, the naphthyl radical or the aromatic benzofused five membered heterocyclic radical containing from 1 to 2 heteroatoms, which may be the same or different from each other, are substituted with one or more halogen atoms, which may be the same or different from each other, and are selected from fluorine, chlorine, bromine and iodine, or with one or more groups, which may be the same or different from each other, and are selected from either linear or branched C 1 -C 5 alkyl or haloalkyl radicals, either linear or branched C 1 -C 5 alkoxy or haloalkoxy radicals; C 3 -C 6 cycloalkyl or cycloalkoxy radicals; C 2 -C 5 carbalkoxy radicals; cyano radicals; methylene dioxyl radicals having the general formula (VI): wherein: R 7 and R 8 , which may be the same or different from each other, represent a hydrogen atom, a fluorine atom; a C 1 -C 3 alkyl or haloalkyl radical. Compounds according to claim 1, in which the phenoxy radical or the thiazolic radical are substituted with one or more halogen atoms, which may be the same or different from each other, and are selected from fluorine, chlorine, bromine and iodine, or with a methyl or trifluoromethyl radical. Compounds according to claim 1, in which R a is: isopropyl, isobutyl, sec.-butyl, tert.-butyl. Compounds according to claim 1, in which the aminoacidic radicals A, when R a represents an alkyl radical are: L-Valine (-L[Val]-), DL-Valine (-DL[Val]) D-Valine (-D[Val]-), Leucine (-[Leu]-), Isoleucine (-[Ile)-), alloIsoleucine (-a[Ile]-), tert.-Leucine (-[Tle]-). Compounds according to claim 1, in which the aromatic penta-membered or hexa-membered heterocyclic radicals containing from 1 to 3 heteroatoms, which may be the same or different from each other, and are selected from nitrogen, oxygen and sulfur, are: pyridine, pyrimidine, pyrrole, imidazole, triazole, thiazole, oxazole, isooxazole. Compounds according to claim 1, in which L, when X represents an oxygen atom, is: methoxy, ethoxy, isopropoxy, tert.-butoxy, benzyloxy. Compounds according to claim 1, in which L, when X represents a -N(R 3 )- moiety, is: methylamino, isopropylamino, butylamino, octylamino, N,N-dimethylamino, piperidyl, morphol-4-yl, benzylamino, 4-chlorobenzylamino, 2,4-dichlorobenzylamino, α-methyl-4-chlorobenzylamino, α-methyl-4-bromobenzylamino, α-methyl-4-methoxy-benzylamino, α-methyl-4-trifluoromethylbenzylamino, thiazol-2-ylamino, imidaz-2-ylamino, α-cyanobenzylamino, α-cyanoisopropylamino, α-carbomethoxyethylamino, α-carboisopropoxy-ethylamino,α-carbomethoxyisobutylamino, 2-carboisopropoxypyrrolid-1-yl, α-(N-methylcarbamoyl)ethylamino, α-carbamoylethylamino, 2-(N,N-dimethylcarbamoylpyrrolid-1-yl), 2-(N,N-diinethylcarbamoylpiperid-1-yl) Compounds according to claim 1, in which L, when X represents an -N(R 4 )-O-moiety, is: methoxyamino, benzyloxyamino, N-methyl-N-benzyloxyamino. Compounds according to claim 1, in which K, when Y represents an oxygen atom, is: carbomethoxy, carboisopropoxy, carboisobutoxy, carbo-tert.-butoxy, carbobenzyloxy, carbophenoxy. Compounds according to claim 1, in which K, when Y represents a direct bond, is: acetyl, isobutanoyl, benzoyl, cyclopropanoyl, 2-methoxy-propanoyl, 2-acetamidopropanoyl, 2-carbomethoxyacetyl. Use as antifungal agents for agricultural purpose of the compounds according to any of claims from 1 to 12. Process for preparing the compounds according to any of claims from 1 to 12, which comprises the condensation reaction of the aminoacidic derivative (VII) and the aminoacidic derivative (VIII): in which K, A, z, B, and w have the same meaning as disclosed hereinabove (K different from hydrogen) in the presence of a condensing agent and a polar solvent, at a temperature comprised within the range of from -10°C up to room temperature. Fungicidal compositions containing one or more compounds according to any of claims 1 to 12, either alone or in the presence of solid carrier, liquid diluents, surfactants or still other active principles. Method for combatting the fungal pests consisting in applying to plants, leaves, stems, branches and roots or to the same seeds before sowing, or to the soil on which the plant grows, fungicidal compositions according to claim 15.

Inventors: CAMAGGI GIOVANNI, FILIPPINI LUCIO, GARAVAGLIA CARLO, GUSMEROLI MARILENA, SIGNORINI ERNESTO, CAMAGGI, GIOVANNI, FILIPPINI, LUCIO, GARAVAGLIA, CARLO, GUSMEROLI, MARILENA, SIGNORINI, ERNESTO
Applicants: ISAGRO SPA, ISAGRO S.P.A.
Application year: 1994
Main classification: C07K5
IPC codes: A01N43, C07K5, A01N47, C07C271, A01N37, C07C237